What is the UN for?

Seriously, it is anything other than a paper tiger these days? It just seems completely toothless given that UNSC permanent members with opposing geopolitical aims can simply veto resolutions they don't like. And even when resolutions are passed, countries with friends in high places routinely ignore them (most egregiously Israel, of course).

Then you've got criticisms like the UNSC membership being essentially a Big Boys' Club of nuclear-armed superpowers and former superpowers, recurrent scandals relating to corruption, child prostitution and so on, and the sick irony of the Saudi presidency of the UNHRC.

So what real purpose does it serve? I don't doubt that some of its subsidiary organs like UNESCO still do valuable work, but as a political and especially a military organisation, the UN itself doesn't seem to have much to argue for its continued existence. Its utter inability to protect the Syrian people from mass murder by their own government is only the most current example of its inadequacy.